Recently, a communications system using ultra-wideband (UWB) characteristics is spotlighted. This is because high-speed wireless communications can be implemented through the utilization of UWB. Accordingly, a UWB system is spotlighted as the next-generation wireless technology based on a commercialized mobile communication network. The UWB system is a high-speed wireless communication technology utilizing a very wide bandwidth, and has been actively studied with much interest together with a wireless personal area network (WPAN) for ultra high-speed data transmission in an indoor wireless environment as a core technology for implementing a sensor network requiring ultra-high-precision resolution and a low-power ubiquitous network.
Until now UWB band-pass filters implemented by using various types of structure have been reported. However, there are problems in that the UWB band-pass filters have very narrow stop-bands and that undesirable pass-bands periodically occur.